as with most of the above posters I just rinse and cut if they happen to be to large
I agree with dogofwar that they are two different species and both are great for fish food
I choose which one i am going to feed acording to the size of the fish just because it would take alot more red wigglers to fill up my 18" Rtc x Tsn hybrid then it would nightcrawlers
but red wigglers do tend to get pounced on quicker but they tend to "squrm" alot more in the tanks water so I think their action attracts the fish ?
I have also caught some of the biggest blue gills I have ever caught using them
I usually squeeze as much of the poop, which is just dirt, out and then scissor it into the right size for which fish Im feeding. I doubt the dirt inside of them is harmful, but I just do it anyways..